1. Field of the Invention
The present invention relates to a web service execution method, a processing method, and an apparatus.
2. Description of the Related Art
Technology is known that reads a structured document (hereunder, referred to as “sequential processing description document”) in which a description has been made for sequentially executing a web service, and sequentially executes a web service in accordance with the description contents thereof. The description in the sequential processing description document is made, for example, in accordance with BPEL (Business Process Execution Language). An information processing apparatus reads the sequential processing description document to execute a web service in which technology such as a sequential processing type of SAX (Simple API for XML) that handles a document as an event stream or DOM (Document Object Model) that handles a document as a tree structure is used.
Regarding the above described type of web service, technology is being developed to solve the problem of how to effectively generate execution procedures of a plurality of web services. Japanese Patent Laid-Open No. 2004-361993 discloses technology that flexibly combines unit flows for performing relatively small processing to dynamically assemble and execute a logical single web service flow as an overall flow. Further, Japanese Patent Laid-Open No. 2005-173892 discloses technology that generates an instruction list that indicates which combination with which to execute processing based on a plurality of instruction lists in which the procedures of individual services are described.
In sequential processing that reads the contents of a structured document in sequence from the top layer part, as typified by SAX, there is a problem that it is difficult to refer to document contents in a position that is forward of the position of the document contents that have been read, that is, to perform forward reference inside a document. More specifically, as the structure of a sequential processing description document becomes more complex, the correspondence by SAX becomes more difficult. This is because, when forward referencing is performed using only the SAX method, it is necessary to make a design regarding with which method description contents that a user wants to reference are to be stored (structured design for data retention) and also with which method those description contents are to be referenced (I/F design).
Further, in a method that performs processing after developing an entire structure that is shown in a sequential processing description document in memory as a structural model, as typified by DOM, there is a problem that if the document contents of a processing object grow to an enormous amount, it puts a squeeze on the memory capacity.